Cement slurry mixing system

ABSTRACT

A slurry reservoir is supplied with a flow of dry bulk cement and mixing water. Mixed slurry from the reservoir is recirculated to a mixing slurry jet disposed in the flow of dry bulk cement and to a plurality of slurry agitator jets disposed within the reservoir, below the surface of the slurry retained therein. The mixing slurry jet cooperates with a mixing water inlet to thoroughly mix the incoming dry bulk cement before the dry bulk cement is added to the slurry in the reservoir. An eductor member, formed with an arcuate vane disposed on a discharge end thereof, may be disposed within the reservoir for providing additional swirling agitation to the body of slurry retained therein. A density measuring device may be connected within the slurry mixing system and used as an indicator by an operator as he varies the inflow of dry cement and water in order to control the final density and quantity of slurry mixed.

United States Patent [72] inventor Donald W. Harriman Duncan, Okla. [21] Appl. No. 819,265 [22] Filed Apr.25, 1969 [45] Patented Feb. 16,197] [73] Assignee Halliburton Company Duncan, Okla.

[54] CEMENT SLURRY MIXING SYSTEM 20 Claims, 4 Drawing Figs.

[52] U.S.Cl. 259/148,

259/161, 259/4 [51] Int.Cl 28c 5/02 [50] Field ol'Search 259/l6l,4, 162,164,165,168,169,170,153,148,147,146, 18, 36

[56] References Cited UNITED STATES PATENTS 2,338,174 l/l944 Garrison 259/95 3,201,093 8/1965 Smith 259/95 3,231,245 l/l966 Harvey 3,256,181 6/1966 Zingg Primary Examiner-Robert W. Jenkins Attorney-Burns, Doane, Benedict, Swecker & Mathis ABSTRACT: A slurry reservoir is supplied with a flow of dry bulk cement and mixing water; Mixed slurry from the reservoir is recirculated to a mixing slurry jet disposed in the flow of dry bulk cement and to a plurality of slurry agitator jets disposed within the reservoir, below the surface of the slurry retained therein. The mixing slurry jet cooperates with a mixing' water inlet'to thoroughly mix the incoming dry bulk cement before the dry bulk cement is added to the slurry in the reservoir. An eductor member, formed with an arcuate vane disposed on a discharge end thereof, may be disposed within the reservoir for providing additional swirling agitation to the body of slurry retained therein. A density measuring device may be connected within the slurry mixing system and used as an indicator by an operator as he varies the inflow of dry cement and water in order to control the final density and quantity of slurry mixed.

PATENTEUF EBJ 6 IBYI 3563517 SHEET 1 UF 2 64 DONALD w. HARRXMANJNVENTOR BY 51MflQ M4MJM+Q ATTORNEYS PATENTEU FEBIBIBYI 3563517 sum 2 0F 2 DONALD w. HARRIMAN 51m, fivm, W, BY MM 1 5 ATTORNEYS BACKGROUND OF THE INVENTION The present invention relates to slurry mixing equipment and, more particularly, to a system for controllably mixing a densified slurry to a desired consistency and density.

Both land based and ofishorei well drilling and completion operations often require on-site cement mixing. With respect to such operations, oil field engineers have recognized that cement mixers should be compact, provide close density control, and possess a high density mixing capability. In order to be practical, such a mixing system, while being compact, must also be capable of mixing substantial quantities of slurry for long periods of time without excessive wear of parts due to abrasion.

In providing a slurry mixer for mixing densified slurry with uniform consistency, three major obstacles must be overcome:

l. Aerated dry pulverized bulk materials exhibit erratic flow characteristics;

2. Cementing materials are characterized by a variation in specific gravity from one batch to the next;

3. The time and energy required to dissolve the various constituents of the dry materials into a pumpable slurry is substantially increased when the density and flow properties'of the slurry depend upon the degree of dissolution of the various included time dependent constituents.

In meeting these requirements, it has been suggested that a large slurry reservoir be provided in the mixing system to allow time for the soluble components of the dry materials to go into solution. Such a large reservoir would also tend to reduce the variation and density of the outgoing slurry caused by the unsteady flow rate of the incoming dry materials and, likewise, would tend to reduce the effect of the variations in specific gravity of the dry material on the final density of the slurry.

When using such an enlarged reservoir, however, additional significant problems are raised.

The addition of a large mixing reservoir to a slurry mixing system requires that some effective means of agitating the slurry retainedin the reservoir be provided in the system for dispersing intermittent large quantities of dry bulk material throughout the body of mixed slurry in the reservoir. Similarly, agitation is required to keep any portion of the slurry mass from solidifying or gelling into a nonpumpable substance.

An upper limit on the density of a mass of mixed slurry is met before obtaining the high density required by current needs without the use of some device to increase the density of the bulk material coming into the reservoir. Therefore, two problems which must be solved before obtaining any of the aforementioned desired results are that of effectively agitating the mass of slurry within the reservoir and of densifying the bulk dry material being supplied tothe reservoir.

It is therefore an object of the present invention to provide an apparatus and a method for mixing dcnsified slurries to higher densities than have heretofore been obtainable.

It is another object of the present invention to provide an apparatus and a method for mixing densified slurries to a more uniform consistency by effective agitation than has heretofore been possible using current devices.

It is still a further object of the present invention to provide an apparatus and a method for mixing densified slurries which invention requires a minimum of equipment so as to be compact and mountable upon wheels or upon an offshore oil well platform.

It is still a further object of the present invention to provide a cement slurry mixing system and method for mixing densitred slurries which system includes means for densifying the dry bulk material before the material is added to the reservoir for mixing.

It is yet a further object of the present invention to provide an apparatus and a method for mixing densified slurries of a uniform consistency using agitating means which will not wear due to abrasion.

SUMMARY OF THE INVENTION Briefly stated, the invention comprises a slurry reservoir, a

.dry material inlet conduit, a mixing water inlet conduit and a pump for both discharging slurry to a work site and for recirculating a portion of the slurry back to the reservoir. The recirculated slurry is used to agitate the mass of slurry retained within the reservoir and is jetted into the dry material conduit with the mixing water in order to mix with and to densify the dry material being supplied to the reservoir.

In one feature of the invention, a density indicator is included in the slurry mixing system and an operator may adjust the final density of the discharged slurry by varying the flow of the dry material and of the mixing water with reference to the indicated density.

In another feature of the invention, an eductor member is disposed below the surface of the slurry within the reservoir. Recirculated slurry is jetted through the eductor to aspirate reservoir retained slurry therethrough. An arcuate discharge conduit is formed on the eductor and operates to impart a swirling motion to the body of slurry in the reservoir In still another feature of the invention, recirculated slurry is jetted toward the mass of slurry surrounding the eductor and acts thereupon; in cooperation with the eductor, to form transverse currents and countercurrents therein.

In yet a further feature of the invention, the arcuate discharge conduit is cut away along an inside curved length thereof which cut away length operates to further influence a swirling motion in the mass of slurry surrounding the eductor.

DRAWINGS OF THE PREFERRED EMBODIMENT While the invention is particularly pointed out and distinctly claimed in theconcluding portion of the specification, the structure and advantages of the preferred embodiment may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a plan view of a preferred embodiment of a slurry cement mixing system in accordance with the present invention;

FIG. 2 is an elevation view of the cement slurry mixing system shown in FIG. 1;

FIG. 3 shows a detail view of a nozzle arrangement used to jet a stream of mixing water and recirculated slurry into an incoming supply flow of dry bulk material in the embodiment shown in FIGS. 1 and 2; and

FIG. 4 shows an alternative embodiment of the present invention, which embodiment is adapted for use in connection with a dry material gravity feed hopper.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in which like numerals are used to indicate like parts throughout the various views thereof, FIGS. 1 and 2 show the preferred embodiment of the present invention as essentially comprising a slurry reservoir 10, a dry material inlet duct 12, a mixing water and recirculated slurry inlet conduit 14, and a combination slurry discharge and recirculation pump 16.

The slurry reservoir 10 is generally rectangular in cross section and is of such dimensions that slurry mixed therein and passing therethrough is retained for a period of time necessary to permit time dependent constituents of the dry material to properly dissolve and/or react. In the specific embodiment exemplified in FIG. I and FIG. 2, the reservoir 10 is open at the top and is filled with slurry up to the liquid surface line indicated as 18 (see FIG. 2).

It should be noted that the discharge end of the dry mate rial inlet conduit 12 'is submerged below the surface 18 of the slurry in the reservoir 10 and, as such, a dust-free operation is provided. To further insure a dust-free operation, the bulk dry material may be supplied to the inlet conduit 12 from an enclosed pressure tank (not shown). Examples of pressure tanks which may be used in this application include the type shown in Us. Pat. No. 3,103,389, issued to J. E. Knight and assigned to the assignee of the present invention. Other examples include the equipment shown in US. Pat. Nos. 2,884,230 and 2,850,329, both of which are issued to E. C. Pyle et al., and assigned to the assignee of the present invention.

As shown in FlG. 2, the bulk, dry material inlet conduit 12 is fonned as a generally, horizontally extending U-shaped pipe with two vertical portions and two horizontal portions. A first 90 elbow 12x immediately precedes one vertically disposed portion 120 of the overall conduit 12 which vertical portion 12a comprises the discharge end of conduit 12. The other vertically disposed section 12b of the horizontally extending U- shaped conduit 12 forms a second 90 elbow 12y with respect to one horizontally disposed portion 12c of the conduit 12 which horizontal portion 12c connects the first and second 90 elbows, 12x and 12y. A ball valve is positioned in the other horizontally extending portion 12d of the conduit 12 which valve 20 is used to control the flow of bulk dry material through the conduit 12 to the reservoir 10.

The mixing water and recirculated slurry inlet conduit 14 is formed with a jet nozzle 22 disposed at the discharge end thereof. Mixing water is added to the conduit 14 through a water collar and annular slot arrangement, shown generally as 23, and discussed in detail later in the disclosure in connection with FIG. 3. The nozzle 22 is positioned within the overall system so as to project into the dry bulk material inlet conduit 12 at the second elbow 12y and is arranged to jet a stream of water and slurry in a direction normal to the flow of bulk dry material passing down through the vertical section 12b of the conduit 12 disposed immediately upstream of the second 90 elbow 12y. This stream of material is also directed along a flow line coincident with the direction of flow bulk material passing through the horizontal section 12c of conduit 12 immediately downstream of the second 90 elbow 12y. The discharge tip of the nozzle 22 is disposed adjacent the center line ofthe conduit 12 so that the bulk material passing thereby is intimately mixed with the incoming jetted slurry and water. The conduit 12 is enlarged at the second 90 elbow 12y to form a mixing bowl 24 which enlargement causes additional turbulence in the area surrounding the nozzle 22. immediately downstream of the mixing bowl 24, the conduit is again narrowed. Through this overall bulk material conduit 12 arrangement, the jet from nozzle 22 aspirates material from upstream of the nozzle and propels the material disposed downstream therefrom.

A mixing water supply conduit 25 is connected with the water collar arrangement 23 at a discharge end thereof and with a water source at the other end, (not shown). A water valve 26 is positioned in the water conduit 25 for controlling the water flow through the jet nozzle 22. An operator may vary the rate of mixing slurry by varying the flow of the water and of the bulk dry material .entering the reservoir 10 by manipulating both valves 26 and 20, respectively. The density of the slurry may be increased by proportionally increasing the rate flow of the bulk dry material with respect to the rate of flow ofthe mixing water.

A discharge conduit 28 is provided and is located near the bottom of the slurry reservoir 10 for removing slurry from the reservoir after it has been properly mixed. The slurry discharge and recirculating pump 16 is connected with the discharge conduit 28 at the suction side thereof. The discharge side of the centrifugal pump 28 is connected with both a down hole slurry supply conduit 30 and a recirculating slurry manifold 32.

A slurry valve 34 is provided in the down hole slurry, supply conduit 30 for controlling the delivery of the thoroughly mixed slurry to the job site. When the valve 34 is closed. all the slurry discharged by the centrifugal pump 16 is delivered to the slurry recirculating manifold 32 for recirculation within the reservoir 10.

As discussed in the background information, it is desirable to increase the density of the bulk cement dry material as it is supplied to the reservoir 10. To partially accomplish this, a

conduit 38 connects the recirculating manifold 32 with the jet nozzle 22. Through this arrangement, a portion of the mixed slurry drawn by the pump 16 is delivered to the jet nozzle 22 and is directed therefrom with mixing water from the water collar arrangement 23 into the dry bulk material passing through the conduit 12. Consequently, the mixed material entering the reservoir 10 through the discharge end 12a of the dry material inlet conduit 12 is of a higher density than that which can be obtained using currently operated mixing systems. Also, the jet nozzle 22 operates to provide a steady flow of dry material through the conduit 12 and thus minimizes the intermittent dry cement flow problem mentioned in the background material.

AGlTATlNG MEANS WITHIN THE SLURRY RESERVOIR in order to thoroughly mix the slurry within the reservoir 10 and in order to keep the slurry in a pumpable state, means are provided for creating streams of slurry within the reservoir 10 which streams interact with each other in a manner which intimately mixes the various constituents carried therein.

The equipment used for accomplishing this in the preferred embodiment, shown in FIGS. 1 and 2, essentially comprises an eductor indicated generally as 40 and a slurry jet agitator system comprising at least one slurry jet 42 positioned within the reservoir 10 and arranged so as to direct a stream of slurry into the body of slurry retained therein. The slurry jet 42 may be referred to as the second slurry jet as the jet from nozzle 22 comprises the first slurry jet.

The slurry jet 42 is connected with the recirculating slurry manifold 32 through a conduit 44. The centrifugal pump 16 provides the head necessary for directing a portion of the slurry, drawn from the reservoir 10, through the slurry discharge conduit 28, through the slurry agitator jet 42 and into the body of slurry contained in the reservoir 10 for creating mixing streams and currents therein. Since no mechanical agitator arms or mixers are required,'the maintenance and replacement of parts due to the abrasion thereof by slurry constituents is precluded. it should be understood, that any number of slurry jet agitators 42 may be used and that these may be directed toward the body of slurry from any angle desired.

EDUCTOR AGITATOR The eductor 40 is generally configured as a right angle conduit member, having a horizontal portion 45 and a vertical portion 46. One slurry inlet 47 is formed on the vertical portion 46 and is spaced directly below and aligned with the discharge end of the dry bulk cement inlet conduit 12. The bottom of the vertical portion 46 of the eductor 40 communicates with the horizontal portion 45 of the overall eductor which horizontal portion 45 is open at both ends 48 and 50. End 48 provides a second, slurry inlet. An arcuate conduit, with a horizontally facing, cutout edge 40a formed along the inside curved portion thereof, comprises a vane 52 formed on the end 50 of the horizontal portion 45 of the eductor 40. The vane 52 extends in generally median alignment with a horizontal plane.

A third slurry jet nozzle 54 is positioned concentrically within the open end 48 of the horizontal portion 45 of the overall eductor 40. The discharge tip of the third slurry jet 54 is disposed in alignment with a plane common to the centerline of slurry flow through the vertical and horizontal portions 46 and 45 of the eductor 40. Thus, the positioning of the jet nozzle 54 is such that it operates to aspirate slurry horizontally through the opening 48 ofthe horizontal portion 45 and down through the vertical portion 46. Upon reaching the tip of the slurry jet nozzle 54, the aspirated slurry is propelled through the remaining length of the horizontal portion 45. The slurry. being propelled out through the opening 50 of the horizontal portion 45 of the eductor 40, is then swirled about the inside face of the arcuate vane 52 and, consequently, forced to flow substantially tangentially therefore at the tip 520 of the vane 52 into the surrounding body of slurry. A low pressure area 40b may tend to be created along the cutout portion 404 of the vane 52 as the fiow of slurry therein jets past the surrounding mass of slurry. This low pressure area 40b, may tend to form vortex currents within the curvature of the vane 52.

As with the first and second slurry jets 22 and 42, the third slurry jet 54 is connected with the recirculating slurry manifold 32 through a connecting conduit 56 projecting through the slurry reservoir wall and connected with the slurry jet nozzle 54. The arcuate vane 52, in the preferred embodiment, is disposed in a generally horizontal plane and is substantially semicircular in cross section. It should be noted, however, that the vane 52 may be disposed in another posture. Optionally, the arcuate vane 52 is tapered or converging along its length toward the discharge end thereof, as shown in FIG. 2 at area 52a.

The stream of slurry directed from the agitator slurry jet 42 is caused to be generally directed toward the tip of the arcuate vane 52 and thus provides additionalinteraction of moving countercurrents and cross currents of slurry in the region surrounding the discharge end 50 of the horizontal portion 45 of eductor 40. In this manner, the slurry is thoroughly mixed to a uniform consistency and due to the recirculation of the slurry into the dry bulk cement inlet 12 highly densified slurries may be obtained.

SLURRY-WATER INLET and annular slot arrangement 23 of the preferred embodiment is provided. In this arrangement, the slurry recirculating conduit 38 carries slurry from the centrifugal pump 16 and is formed with an annular slot 58 disposed near the discharge end thereof. A water and slurry outlet 59 comprising jet nozzle 22, is formed at the discharge end of the conduit 38 and is operable to direct a jet of slurry and water into the dry material inlet conduit 12 and to intimately mix the dry material with slurry and water at the mixing bowl 24.

In order to provide water for the mixing operation, an annular water collar 60 is formed around the annular slot 58 and is connected with a water source (not shown) through the water conduit 25. I

In operation, as slurry is forced through the nozzle 59 of the slurry conduit 38 into the mixing bowl 24, it aspirates water from the annular water collar 60 through the annular slot 58. Simultaneously, the water pressure provided by the water source may be used to force water through the annular slot 58 into the stream of slurry carried by the conduit 38. As an overall result, a water "coating" is thereby formed on the stream of jetted slurry, which coating is effective, as ,a generally annular interface between slurry and dry bulk cement, to combine and mix with the dry bulk material passing through the mixing bowl 24. The dense mass of slurry inside the water coating is effective toassist the flow of bulk material through the conduit 12 and to supply a more densified inlet bulk material to the reservoir 10.

An alternative configuration to accomplish the desired result would be to position the slurry jet nozzle 59 concentrically within a larger water nozzle so as to form a slurry nozzle surrounded by an annular water nozzle.

METHOD OF OPERATION WITH PREFERRED EMBODIMENT ln practicing the present invention using the preferred embodiment shown in FIGS. 1 and 2, a minimum amount of water necessary to allow recirculation through the overall system is placed in the reservoir from the mixing water inlet 25. The pump 16 is started in order to begin recirculation. and the ball valve 20 is opened to allow dry bulk material to enter the mixing bowl 24. As mentioned previously, in order to provide a completely dust-free operation, a pressurized bulk storage vessel may be used in connection with the overall cement slurry mixing system.

During this early period of initial mixing, a density measuring device 64 may be used to continuously monitor the density of the slurry as it is being recirculated to the reservoir 10. FIG. 2 shows a pump 66, at the bottom of the reservoir 10, which pump 66 is used to deliver a portion of the slurry, being drawn into the discharge pump 16, to the densometer 64 for monitoring. On systems in accordance with the preferred embodiment, the inventor uses a Halliburton 62-DIA densometer obtainable from Halliburton Services, of Duncan, Oklahoma. When the slurry density reaches a desired level, the valve 34 to the work site is opened to allow the slurry to be pumped to the well or to whatever the work site happens to be. When used in well construction applications, a down hole pump (not shown) may also be included in the down hole conduit 30 downstream from the valve 34 in order to pressurize the down hole.

While the slurry is being pumped to the work site, additional mixing water may be added to the system by opening the water valve 26 within the water mixing inlet 25. This action provides additional water to be jetted into the mixing bowl 24 of the bulk dry material inlet conduit 12.

The system is now in condition for continual operation with a portion of the mixed slurry being pumped to the work site and the remaining slurry being recirculated for densifying the dry bulk material being discharged into the reservoir 10, for a p.s.i. and propelling slurry through the eductor 40, and for agitating the mass of slurry retained in the reservoir 10. The density of the slurry may be controlled by regulating the proportion of flow of the bulk material with respect to the water flow entering the overall mixing system. To increase the output of slurry, naturally, both the water and bulk material valves 26 and 20, respectively, would be opened the desired amount. Other valves, (not shown) could be added to the various conduits supplying slurry to the slurry jets to lend more flexibility to the overall operation.

ALTERNATIVE EMBODIMENT OF SLURRY MIXING SYSTEM FIG. 4 shows an alternative overall embodiment of a slurry mixing system, according to the present invention, which alternative embodiment is especially adapted for operation with a gravity feed hopper as a means for supplying dry bulk cement to the system.

A slurry reservoir is provided and is generally rectangular in cross section. Once again, the size of the reservoir, the distance between inlet and outlet and the agitation of the slurry in the reservoir is such that the constituents of the slurry passing therethrough are permitted a sufficient period of time for any time dependent ingredients contained therein to properly dissolve orreact. Bulk dry material is added to a gravity feed hopper 102 which is funnellike in configuration and is connected with the slurry reservoir 100 through a bulk dry material supply conduit 104.

The connection of the gravity feed hopper 102 with the conduit 104 is at the bottom of the gravity feed hopper and forms a mixing bowl region 103 which is similar in appearance and operation to the mixing bowl 24 of the preferred embodiment of FIGS. 1 and 2.

A mixing jet 106 projects into the region of the mixing bowl 103 and directs a stream'of water and slurry in a direction normal to the gravity feed flow of the dry material and longitudinally downstream within a horizontal portion 104a of the dry material supply conduit 104. The jet 106 is disposed immediately below the gravity feed hopper 102 and as such, aspirates dry material through the funnellike gravity feed hopper 102 and propels the bulk dry material downstream through the conduit 104 after mixing therewith in the mixing bowl region 103.

The bulk dry material supply inlet conduit 104 runs substantially horizontally upstream from the gravity feed hopper 102 for the first portion 104a of its length. After this first portion 104a of length, however, the conduit 104 at portion 104b is inclined at about 45 to an upper point on the reservoir 100 where the conduit 104 is mounted to the reservoir 100 and projects therethrough at a downwardly curved discharge end 105 thereof. The velocity of the constituents propelled through the conduit 104 by the mixing jet 106 may not be sufficient to carry the bulk dry cement, slurry and mixing water up the inclined portion 104b of theconduit 104. Therefore, a booster jet 108 is provided at the bottom of the inclined portion of the conduit 104 and operates to direct additional recycled slurry downstream through the conduit 104. The booster jet 108 is only necessary when the bulk material hopper 102 is disposed below the level of the reservoir as is the case in many minimum area work sites such as oil well platforms. Of course, the booster jet 108 also provides additional mixing and further densifies the bulk material as it directs recycled slurry into the supply inlet conduit 104.

As in the preferred embodiment of FIGS. 1 and 2, a discharge conduit 110 is provided near the bottom of the slurry reservoir 100 and is connected with the suction side of a centrifugal slurry pump 112. The discharge side of the centrifugal slurry pump 112 is connected with a recirculated slurry manifold 114 through a slurry conduit 116 disposed therebetween. One end of the slurry manifold 114 is connected with a down hole conduit 117 through a slurry valve 118, which conduit 117 carries discharged slurry to a work site. If the work site should be an oil well, an additional down hole pump (not shown) may be provided to facilitate the delivery of slurry and to pressurize the down hole.

The mixing jet 106 projecting into the mixing bowl 103, disposed immediately beneath the gravity feed hopper 102, is connected with the slurry manifold through a conduit 120 which provides for the recirculation of slurry from the centrifugal slurry pump 112, through the mixing jet 106, back into the reservoir 100 through the dry bulk material inlet 104. Mixing water is provided to the mixing jet 106 through a water conduit 122 which communicates with the slurry conduit 120 immediately upstream of the nozzle 106 at fitting 124.

The connection of the mixing water conduit 122 with the recirculated slurry conduit 120 at the fitting 124 may be configured according to the embodiment shown in FIG. 3, may comprise concentric nozzles as previously discussed or may even be merely a T fitting whereby the water is fed directly into the slurry conduit 120 connecting the nozzle 106 with the slurry manifold 114. The slurry booster jet 108 is likewise sealingly connected with the slurry manifold 114 through a conduit 126 provided with a valve 128. This valve may be used for shutting off the booster jet 108 if the jet need not be utilized for driving the dry bulk material up the inclined portion l04b of the bulk material supply conduit 104.

Conduit l04b may terminate in a downwardly facing outlet 105 corresponding to outlet 12a of the FIGS. 1 and 2 embodiment. A conduit I30 extending from manifold 114 may supply slurry to a jet pump within reservoir 100 in the same manner as conduit 56 supplies slurry to jet pump 40 of the FIG. 1-2 embodiment. Discharge outlet 105 would be superposed above the vertical inlet to the jet pump in the same way that outlet 12a serves to direct slurry toward inlet 47 of jet pump 40. Another conduit 132, extending from manifold 114, may feed an agitating jet corresponding to jet 42 of the FIG. l-2 embodiment. The agitating jet and jet pump arrangement within reservoir 100 would be essentially the same as that shown in FIGS. 1-2.

The flow of recirculated slurry through conduits 130 and 132 may be selectively controlled by valves 134 and 136, respectively.

In operation, if it should be desired to operate the FIG. 4 system without using the entire recirculating feature, any of the valves 128. 134. and 136 may be closed. Indeed, all of the slurry drawn by the centrifugal slurry pump 112 could be directed to the work site, with the exception of a small portion thereof being carried off through conduit 120 to operate the mixing jet 106 connected therewith and disposed within the mixing bowl region 103.

Conversely, if it should be desired to operate the system using the entire recirculating slurry feature, valves 128, 134 and 136 would be opened and the jets controlled by these valves thereby activated.

In order to mix slurry using this alternative embodiment of the invention, dry bulk material is poured into the gravity feed hopper 102. The material then flows therefrom into the mixing bowl 103 where it is intimately mixed with water and recirculated slurry through the operation of the mixing jet 106. The overall mixture is propelled by the jet 106 downstream to the portion l04b where the conduit 104 is inclined upward at which portion 104b the booster jet 108 directs an additional stream of slurry into the material fiow. The booster jet 108 operates to provide additional mixing to the system and further operates to propel the material up the incline and into the reservoir 100, The discharge end 105 of conduit 104 directs the bulk material down toward the bottom of the reservoir and toward the jet pump. In order to reduce the amount of dust, the discharge end should be submerged under the surface of the reservoir slurry as in the preferred embodiment.

Within the reservoir 100, the slurry flows through the jet pump and is acted upon by the agitating jet to create crosscurrents and countercurrents therein. As previously discussed, the distance between the slurry inlet and outlet of the reservoir, acting in cooperation with the agitating action, is such that the time dependent constituents of the slurry are provided time to dissolve or react.

Upon being discharged, the slurry is drawn through the slurry pump 112 and directed to the slurry manifold 114. From the manifold 114, a major portion of the slurry may be directed to the work site through the down hole valve 118 and the down hold conduit 116. The remaining portion of the slurry is recirculated, as previously described, through the mixing jet 106, the slurry booster jet 108 and the conduits and 132.

SUMMARY OF ADVANTAGES AND SCOPE OF INVENTION It can thus be seen that an improved apparatus and method has been provided for mixing slurry. Due to the incorporation of a slurry recirculation feature, highly densified slurry is now obtainable. The use of various agitating devices including eductors, aspirators, agitating slurry jets and a mixing bowl, ensure a uniformly consistent flow of slurry to a work site. Since the components of the mixing system of the present invention are carefully chosen to form a compact unit, the overall mixing system may be mounted on a wheeled cart or skid or located on a minimum area work site such as an offshore oil well platform.

The current upper limit on the density of slurry caused by the low density of incoming dry bulk material has been substantially lifted by jetting a stream of recirculated slurry into the dry bulk supply conduit leading to the mixing reservoir. This arrangement also ensures a more steady flow of dry material to the slurry reservoir than is now possible using pressurized dry material supply tanks or gravity feed hoppers without such an arrangement.

The slurry-water inlet uniquely densifies the incoming slurry while effecting immediate mixing of the water and dry cement.

The jet pump provides a novel arrangement for aspirating and agitating slurry within the reservoir on a multidirectional asis.

Since no mechanical arms or mixers are utilized in the system contemplated by the present invention, repair and replacement of equipment due to abrasion is held to a minimum. The various currents of slurry caused within the reservoir by the recirculated slurry are effective to preclude any gelling of any portion of the body of slurry retained within the reservoir, which gelling would render the slurry to be nonpumpable.

While what has been shown and described comprises a preferred embodiment of the invention and a modification thereof, it is, of course, understood that various other changes and modifications may be made therein without departing from the substance of the invention. Therefore, it is intended to cover in the appended claims all such apparatus and methods as fall within the spirit and scope of the present invention.

lclaim: I

l. A slurry mixing system comprising:

a. a slurry reservoir;

b. a bulk material supply means communicating with said slurry reservoir;

c. mixing water supply means communicating with said reservoir and adapted for connection with a water source;

d. slurry recirculating means for returning discharged mixed slurry to said slurry reservoir;

e. first slurry jet nozzle means projecting into said bulk material supply means;

f. said first slurry jet nozzle means connected with said slurry recirculating means;

g. said mixing water supply means connected with said first slurry jet nozzle;

h. valve means for adjusting the flow of bulk material and mixing water supplied to said reservoir whereby the quantity and density of slurry mixed in said reservoir may be controlled; and

i. slurry discharge means for removing slurry from said reservoir and delivering it to a point remote therefrom.

2. A slurry mixing system according to claim 1 wherein:

a. first and second elbows are formed in said bulk material supply means; 7

. b. a substantially horizontal portion of said bulk material supply means extends between said first and said second elbows;

c. said valve means for adjusting the flow of bulk material is disposed above said second elbow;

d. a mixing bowl region is formedatsaid second elbow;

e. said first slurry jet nozzle means projects into said bulk material supply means at said mixing bowl region and is positioned to direct slurry, mixing water and bulk material through said substantially horizontal portion of said bulk material supply means toward said first elbow;

f. a substantially vertical discharge portion of said bulk material supply means extends below said first elbow and is positioned to direct materials carried therethrough into said slurry reservoir.

3. A slurry mixing system according to claim 1 with the addition of agitating means in said reservoir for mixing slurry contained therein.

4. A slurry mixing system according to claim 3 wherein said agitating means comprises a second slurry jet nozzle means disposed within said slurry reservoir with the addition of, conduit means for connecting said second slurry jet nozzle means with said slurry recirculating means whereby streams of slurry may be created within said reservoir to agitate slurry contained therein.

5. A slurry mixing system according to claim 4 wherein said second slurry jet nozzle means disposed within said slurry reservoir is positioned beneath the surface of the slurry contained therein and is directed generally toward a bottom of said slurry reservoir.

6. A slurry mixing system according to claim 3 with the addition of eductor means disposed beneath a discharge end of said dry material supply means.

7. A slurry mixing system according to claim 5 wherein said eductor means is vertically spaced from the discharge end of said dry material supply means.

8. A slurry mixing system according to claim 7 wherein said bulk material supply means is connected with a pressurized bulk material tank.

9. A slurry mixing system according to claim 7 wherein said dry material supply means is connected with a gravity feed hopper and with the addition of:

a. a booster jet projection Tara said bulk material supply means;

b. a downstream portion of said bulk material supply means being inclined upward into said slurry reservoir;

c. said booster jet disposed at an upstream end of the portion of said bulk material supply means being inclined upward;

d. said booster jet being connected with said slurry recirculation means; and

e. said booster jet being operable to further mix slurry with the bulk material passing thereby and for propelling the combined slurry and bulk material into said reservoir.

10. A slurry mixing system according to claim 7 wherein said eductor means comprises: I

a. a horizontally extending conduit having first and second ends;

b. an arcuate vane formed on said first end;

c. said first and second ends opened to provide slurry passage therethrough;

d. a vertically opened conduit formed on said horizontally extending conduit and aligned with the discharge end of said dry material supply means;

v e. a third slurry jet nozzle means projecting into said second end of said horizontally extending conduit and disposed concentrically therein;

f. conduit means connecting said third slurry jet means with said slurry recirculating means, whereby a stream of slurry directed from said third slurry jet means aspirates slurry from said slurry reservoir through said vertically opened conduit and through said second open end of said horizontally extending conduit and directs the combined mixture of slurry out said first open end against said arcuate vane.

II. A slurry mixing system according to claim 10 with said arcuate vane being:

a. disposed in a horizontal plane;

b. provided with a semicircular cross section; and

c. tapered toward a discharge end thereof.

12. A slurry mixing system according to claim 10 wherein said slurry recirculating means includes:

a. a centrifugal pump with suction and discharge sides;

b. said suction side being connected with said slurry discharge means; and

c. said discharge side being connected with said first, second and third slurry jet means.

13. A slurry mixing system according to claim 12 wherein said reservoir slurry discharge means connects with a downhole conduit through said centrifugal pump; and a stop valve is provided in said downhole conduit for shutting off slurry discharge to said downhole conduit for providing all the slurry to said first, second and third slurry jet means.

14. Nozzle apparatus comprising:

a. liquid supply means;

b. a media nozzle;

0. said liquid supply means being operable to be connected with a liquid source;

d. said media n'ozzlebeing operable to be connected with a media recirculating system;

c. bulk material supply means; and

f. a mixing chamber operable to concurrently receive liquid from said liquid supply means, and media from said media nozzle, as a concurrent flow and direct said concurrent flow transversely of a flow of bulk material from said bulk material supply means.

15. A jet nozzle for use in cement slurry mixers incorporating a slurry recirculation feature comprising:

a. a slurry nozzle;

b. said slurry nozzle being formed with annular slots disposed immediately upstream from a discharge end thereof;

c. an annular water collar;

d. said annular water collar being positioned around said slurry nozzle so as to cover the annular slots;

c. said annular water collar being connected with a water source;

f. said slurry nozzle being connected with a slurry recirculating system ofa slurry mixer;

g. said slurry nozzle being operable to direct a jet of combined water and slurry into a flow of material passing thereby.

16. An agitating apparatus for mixing media, said apparatus comprising:

a. first conduit means operable to communicate with a first zone within said media;

b. second conduit means operable to communicate with a second zone within said media and communicating with said first conduit means;

c. jet means operable to impel media through each of said first and second conduit means;

d. media discharge means; and' e. said first and second conduit means being mutually inclined and communicating with said media discharge means.

17. An agitating apparatus according to claim 16 wherein said media discharge means comprises:

a. a curved discharge guide; and

b. said curved discharge guide having an at least partially open, inside curved portion.

18. An agitating apparatus according to claim 16 further comprising; agitator jet means operable to direct media generally toward, and countercurrent with respect to, media issuing from said discharge means.

19. A method for mixing a densified media comprising the steps of:

a. providing a media mixing reservoir;

b. supplying mixing liquid to the reservoir;

c. supplying a flow of bulk material to the reservoir;

d. recirculating a portion of the media mixed in the reservoir out through a reservoir discharge conduit and back into the reservoir;

e. mixing the bulk material with mixing liquid and recirculated media before supplying the bulk material to the reservoir; and

f. agitating media in the reservoir with recirculated media.

20. A method for agitating media comprising the steps of:

a. converging and uniting flows of media from diverse zones within a media reservoir;

b. agitating said media within said reservoir with said united flows; and

c. inducing said converging flows of media with at least one jet of said media disposed in aspirating cooperation with said media. 

1. A slurry mixing system comprising: a. a slurry reservoir; b. a bulk material supply means communicating with said slurry reservoir; c. mixing water supply means communicating with said reservoir and adapted for connection with a water source; d. slurry recirculating means for returning discharged mixed slurry to said slurry reservoir; e. first slurry jet nozzle means projecting into said bulk material supply means; f. said first slurry jet nozzle means connected with said slurry recirculating means; g. said mixing water supply means connected with said first slurry jet nozzle; h. valve means for adjusting the flow of bulk material and mixing water supplied to said reservoir whereby the quantity and density of slurry mixed in said reservoir may be controlled; and i. slurry discharge means for removing slurry from said reservoir and delivering it to a point remote therefrom.
 2. A slurry mixing system according to claim 1 wherein: a. first and second elbows are formed in said bulk material supply means; b. a substantially horizontal portion of said bulk material supply means extends between said first and said second elbows; c. said valve means for adjusting the flow of bulk material is disposed above said second elbow; d. a mixing bowl region is formed at said second elbow; e. said first slurry jet nozzle means projects into said bulk material supply means at said mixing bowl region and is positioned to direct slurry, mixing water and bulK material through said substantially horizontal portion of said bulk material supply means toward said first elbow; f. a substantially vertical discharge portion of said bulk material supply means extends below said first elbow and is positioned to direct materials carried therethrough into said slurry reservoir.
 3. A slurry mixing system according to claim 1 with the addition of agitating means in said reservoir for mixing slurry contained therein.
 4. A slurry mixing system according to claim 3 wherein said agitating means comprises a second slurry jet nozzle means disposed within said slurry reservoir with the addition of, conduit means for connecting said second slurry jet nozzle means with said slurry recirculating means whereby streams of slurry may be created within said reservoir to agitate slurry contained therein.
 5. A slurry mixing system according to claim 4 wherein said second slurry jet nozzle means disposed within said slurry reservoir is positioned beneath the surface of the slurry contained therein and is directed generally toward a bottom of said slurry reservoir.
 6. A slurry mixing system according to claim 3 with the addition of eductor means disposed beneath a discharge end of said dry material supply means.
 7. A slurry mixing system according to claim 5 wherein said eductor means is vertically spaced from the discharge end of said dry material supply means.
 8. A slurry mixing system according to claim 7 wherein said bulk material supply means is connected with a pressurized bulk material tank.
 9. A slurry mixing system according to claim 7 wherein said dry material supply means is connected with a gravity feed hopper and with the addition of: a. a booster jet projection into said bulk material supply means; b. a downstream portion of said bulk material supply means being inclined upward into said slurry reservoir; c. said booster jet disposed at an upstream end of the portion of said bulk material supply means being inclined upward; d. said booster jet being connected with said slurry recirculation means; and e. said booster jet being operable to further mix slurry with the bulk material passing thereby and for propelling the combined slurry and bulk material into said reservoir.
 10. A slurry mixing system according to claim 7 wherein said eductor means comprises: a. a horizontally extending conduit having first and second ends; b. an arcuate vane formed on said first end; c. said first and second ends opened to provide slurry passage therethrough; d. a vertically opened conduit formed on said horizontally extending conduit and aligned with the discharge end of said dry material supply means; e. a third slurry jet nozzle means projecting into said second end of said horizontally extending conduit and disposed concentrically therein; f. conduit means connecting said third slurry jet means with said slurry recirculating means, whereby a stream of slurry directed from said third slurry jet means aspirates slurry from said slurry reservoir through said vertically opened conduit and through said second open end of said horizontally extending conduit and directs the combined mixture of slurry out said first open end against said arcuate vane.
 11. A slurry mixing system according to claim 10 with said arcuate vane being: a. disposed in a horizontal plane; b. provided with a semicircular cross section; and c. tapered toward a discharge end thereof.
 12. A slurry mixing system according to claim 10 wherein said slurry recirculating means includes: a. a centrifugal pump with suction and discharge sides; b. said suction side being connected with said slurry discharge means; and c. said discharge side being connected with said first, second and third slurry jet means.
 13. A slurry mixing system according to claim 12 wherein said reservoir slurry discharge means connects with a downhole conduit through said centrifugal pump; and a stop valVe is provided in said downhole conduit for shutting off slurry discharge to said downhole conduit for providing all the slurry to said first, second and third slurry jet means.
 14. Nozzle apparatus comprising: a. liquid supply means; b. a media nozzle; c. said liquid supply means being operable to be connected with a liquid source; d. said media nozzle being operable to be connected with a media recirculating system; e. bulk material supply means; and f. a mixing chamber operable to concurrently receive liquid from said liquid supply means, and media from said media nozzle, as a concurrent flow and direct said concurrent flow transversely of a flow of bulk material from said bulk material supply means.
 15. A jet nozzle for use in cement slurry mixers incorporating a slurry recirculation feature comprising: a. a slurry nozzle; b. said slurry nozzle being formed with annular slots disposed immediately upstream from a discharge end thereof; c. an annular water collar; d. said annular water collar being positioned around said slurry nozzle so as to cover the annular slots; e. said annular water collar being connected with a water source; f. said slurry nozzle being connected with a slurry recirculating system of a slurry mixer; g. said slurry nozzle being operable to direct a jet of combined water and slurry into a flow of material passing thereby.
 16. An agitating apparatus for mixing media, said apparatus comprising: a. first conduit means operable to communicate with a first zone within said media; b. second conduit means operable to communicate with a second zone within said media and communicating with said first conduit means; c. jet means operable to impel media through each of said first and second conduit means; d. media discharge means; and e. said first and second conduit means being mutually inclined and communicating with said media discharge means.
 17. An agitating apparatus according to claim 16 wherein said media discharge means comprises: a. a curved discharge guide; and b. said curved discharge guide having an at least partially open, inside curved portion.
 18. An agitating apparatus according to claim 16 further comprising; agitator jet means operable to direct media generally toward, and countercurrent with respect to, media issuing from said discharge means.
 19. A method for mixing a densified media comprising the steps of: a. providing a media mixing reservoir; b. supplying mixing liquid to the reservoir; c. supplying a flow of bulk material to the reservoir; d. recirculating a portion of the media mixed in the reservoir out through a reservoir discharge conduit and back into the reservoir; e. mixing the bulk material with mixing liquid and recirculated media before supplying the bulk material to the reservoir; and f. agitating media in the reservoir with recirculated media.
 20. A method for agitating media comprising the steps of: a. converging and uniting flows of media from diverse zones within a media reservoir; b. agitating said media within said reservoir with said united flows; and c. inducing said converging flows of media with at least one jet of said media disposed in aspirating cooperation with said media. 